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authorlloyd <[email protected]>2014-01-10 03:41:59 +0000
committerlloyd <[email protected]>2014-01-10 03:41:59 +0000
commit6894dca64c04936d07048c0e8cbf7e25858548c3 (patch)
tree5d572bfde9fe667dab14e3f04b5285a85d8acd95 /src/lib/entropy/entropy_src.h
parent9efa3be92442afb3d0b69890a36c7f122df18eda (diff)
Move lib into src
Diffstat (limited to 'src/lib/entropy/entropy_src.h')
-rw-r--r--src/lib/entropy/entropy_src.h141
1 files changed, 141 insertions, 0 deletions
diff --git a/src/lib/entropy/entropy_src.h b/src/lib/entropy/entropy_src.h
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+++ b/src/lib/entropy/entropy_src.h
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+/*
+* EntropySource
+* (C) 2008-2009 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_ENTROPY_SOURCE_BASE_H__
+#define BOTAN_ENTROPY_SOURCE_BASE_H__
+
+#include <botan/buf_comp.h>
+#include <string>
+
+namespace Botan {
+
+/**
+* Class used to accumulate the poll results of EntropySources
+*/
+class BOTAN_DLL Entropy_Accumulator
+ {
+ public:
+ /**
+ * Initialize an Entropy_Accumulator
+ * @param goal is how many bits we would like to collect
+ */
+ Entropy_Accumulator(size_t goal) :
+ entropy_goal(goal), collected_bits(0) {}
+
+ virtual ~Entropy_Accumulator() {}
+
+ /**
+ * Get a cached I/O buffer (purely for minimizing allocation
+ * overhead to polls)
+ *
+ * @param size requested size for the I/O buffer
+ * @return cached I/O buffer for repeated polls
+ */
+ secure_vector<byte>& get_io_buffer(size_t size)
+ { io_buffer.resize(size); return io_buffer; }
+
+ /**
+ * @return number of bits collected so far
+ */
+ size_t bits_collected() const
+ { return static_cast<size_t>(collected_bits); }
+
+ /**
+ * @return if our polling goal has been achieved
+ */
+ bool polling_goal_achieved() const
+ { return (collected_bits >= entropy_goal); }
+
+ /**
+ * @return how many bits we need to reach our polling goal
+ */
+ size_t desired_remaining_bits() const
+ {
+ if(collected_bits >= entropy_goal)
+ return 0;
+ return static_cast<size_t>(entropy_goal - collected_bits);
+ }
+
+ /**
+ * Add entropy to the accumulator
+ * @param bytes the input bytes
+ * @param length specifies how many bytes the input is
+ * @param entropy_bits_per_byte is a best guess at how much
+ * entropy per byte is in this input
+ */
+ void add(const void* bytes, size_t length, double entropy_bits_per_byte)
+ {
+ add_bytes(reinterpret_cast<const byte*>(bytes), length);
+ collected_bits += entropy_bits_per_byte * length;
+ }
+
+ /**
+ * Add entropy to the accumulator
+ * @param v is some value
+ * @param entropy_bits_per_byte is a best guess at how much
+ * entropy per byte is in this input
+ */
+ template<typename T>
+ void add(const T& v, double entropy_bits_per_byte)
+ {
+ add(&v, sizeof(T), entropy_bits_per_byte);
+ }
+ private:
+ virtual void add_bytes(const byte bytes[], size_t length) = 0;
+
+ secure_vector<byte> io_buffer;
+ size_t entropy_goal;
+ double collected_bits;
+ };
+
+/**
+* Entropy accumulator that puts the input into a Buffered_Computation
+*/
+class BOTAN_DLL Entropy_Accumulator_BufferedComputation :
+ public Entropy_Accumulator
+ {
+ public:
+ /**
+ * @param sink the hash or MAC we are feeding the poll data into
+ * @param goal is how many bits we want to collect in this poll
+ */
+ Entropy_Accumulator_BufferedComputation(Buffered_Computation& sink,
+ size_t goal) :
+ Entropy_Accumulator(goal), entropy_sink(sink) {}
+
+ private:
+ void add_bytes(const byte bytes[], size_t length) override
+ {
+ entropy_sink.update(bytes, length);
+ }
+
+ Buffered_Computation& entropy_sink;
+ };
+
+/**
+* Abstract interface to a source of entropy
+*/
+class BOTAN_DLL EntropySource
+ {
+ public:
+ /**
+ * @return name identifying this entropy source
+ */
+ virtual std::string name() const = 0;
+
+ /**
+ * Perform an entropy gathering poll
+ * @param accum is an accumulator object that will be given entropy
+ */
+ virtual void poll(Entropy_Accumulator& accum) = 0;
+
+ virtual ~EntropySource() {}
+ };
+
+}
+
+#endif